1. Field of the Invention
The present invention relates to the field of patient ventilators and membrane switches. More particularly, the invention is concerned with a patient ventilator connected to two stand-by switches wherein activation of both switches is required for stopping the ventilating function. The preferred stand-by switches are in the form of membrane switches in which a conductive dome is positioned and spaced between respective layers having electrical traces thereon cooperating with the dome for defining the switches. The application of manual pressure closes the spaces between the layers and activates both switches.
2. Description of the Prior Art
Patient ventilators assist or totally provide the respiratory function for a patient. If a single stand-by switch is used for stopping the ventilating function, there is a risk that a defect in the switch, such as a short circuit, could cause the ventilator to stop. The prior art solves this problem with a rotary switch mechanism having two stand-by switches in which activation of both switches is required for stopping the ventilating function. Those skilled in the art appreciate, however, that rotary switch mechanisms tend to be bulky and uneconomical, especially for the smaller sized home ventilators.